An optical matrix device with a two-dimensional matrix arrangement of elements relating to light and having active elements formed of thin-film transistors (TFTs) or the like and capacitors is in wide use today. Light receiving elements and display elements may be cited as examples of the elements relating to light. This optical matrix device is divided roughly into a device formed of light receiving elements, and a device formed of display elements. The device formed of light receiving elements includes an optical image sensor, and a radiation image sensor used in the medical field, industrial field or the like. The device formed of display elements includes an image display used as a television or a monitor of a personal computer, such as the liquid crystal type having elements which adjust the intensity of transmitted light and the EL type having light emitting elements. Light here refers to infrared light, visible light, ultraviolet light, radiation (X-rays, gamma rays) and so on.
In recent years, a method of using the inkjet technique has been studied vigorously as a method of forming wires of an active matrix substrate provided for such an optical matrix device. The inkjet technique can form not only the wires such as gate lines and data lines of the active matrix substrate, but also semiconductors such as gate channels. It is very useful in that, unlike the conventional photolithographic technique, it can carry out direct printing and does not need photomasks. For such reasons, this technique is expected to realize active matrix substrates of large area.
With the inkjet printing technique, semiconductor film, insulator film or conducting wires can be formed by carrying out printing and coating of droplets (ink) containing semiconductor, insulator or conductive particles on an insulating substrate. Droplets ejected from an ink jet nozzle are maintained as a solution or in a colloidal state by dissolving or dispersing either the semiconductor, insulator or conductive particles in an organic solvent. And after printing and coating these droplets, the organic solvent is volatized by heating treatment to form semiconductor film, insulator film or conducting wires (wiring).
Patent Document 1, for example, discloses a thin-film transistor manufacturing method which forms thin-film transistors of the bottom gate type by inkjet technique.
[Patent Document 1]
Japanese Unexamined Patent publication No. 2004-349583